Update at 1:00 p.m.: Prosecutors played DART surveillance video in court this morning that showed a gunman fatally shoot Dominique Wilson from aboard a light-rail train.

That gunman was later identified by police as Joshua Tyrone Mathis, who silently watched the video in his murder trial. Videos from several different angles appeared to show a group of men including Mathis exchanging words with a group including Wilson.

A train pulled up and Mathis and his friends got on board. Wilson appeared to continue to talk and point toward Mathis from the station platform.

The train doors closed, but within seconds they reopened, apparently because someone on board pushed a button to open them. It appeared that someone was trying to hold Wilson back from approaching the train door, but he got by and walked toward the open door with his hands down at his side.

That’s when the gunman fired, striking Wilson and knocking him to the ground. Witnesses could be seen running from the scene. At least two people approached Wilson, who laid motionless.

But it was also a relatively rare incident of deadly violence between two men who reportedly traded insults just before the shooting.

We’ll likely soon learn more about what transpired that night, as testimony is scheduled to begin this morning in the trial of the man charged with murder in that slaying, Joshua Tyrone Mathis, 21. The slaying was caught on DART surveillance video.

Mathis faces up to life in prison if convicted. He is being held at the Lew Sterrett Justice Center, where his bail is set at $100,000.